In this study, the influence of self-weight exercise on changes in the bone mass was evaluated in young Japanese women. The subjects were 69 female university students(age: 21.20±0.30). They were assigned to an exercise intervention (Ex, n=26) or control(C, n=43) group according to their requests. Group Ex performed two sets of 10 sit-up, 10 back-extensions, and 10 squats every day for six months. The height, weight, body fat percentage (TANITA, TBF102), bone mass (quantitative ultrasound, Lunar, A-1000EXPRESS), and urinary deoxypyridinoline (DPD) were measured, and their previous and present exercise habits were examined. Group Ex showed no differences in the bone mass or DPD after the training. Group C, on the other hand, showed a significant decrease in the bone mass (p<0.01) and an increase in DPD (p<0.01) after the training. It was suggested that the bone mass can be possibly maintained through self-weight exercise.